rsync - Jun 2003 - unexplained error (code 23) at main.c(1045)

I am using rsync 2.5.6 to copy from a system running redhat 6.2
(192.168.0.50) to another system running redhat 6.2 (192.168.0.70).

The command line I'm using is:
rsync -avW --numeric-ids --delete 192.168.0.50::vgroup00/* /vgroup00/

It complains

IO error encountered - skipping file deletion
rsync error: some files could not be transferred (code 23) at main.c(1045)

I looked at main.c(1045) and it is exit_cleanup(ret) which doesn't really
help much.
Does anyone know what kind of error this might be?

Thanks,
Eric